The Dale Oil Field, Caldwell County, Texas

Geological Science

Stationary distributions of the multi-type ASEP

We give a recursive construction of the stationary distribution of multi-type asymmetric simple exclusion processes on a finite ring or on the infinite line $Z$. The construction can be interpreted in terms of "multi-line diagrams" or systems of queues in tandem. Let $q$ be the asymmetry parameter of the system. The queueing construction generalises the one previously known for the totally asymmetric ($q=0$) case, by introducing queues in which each potential service is unused with probability $q^k$ when the queue-length is $k$. The analysis is based on the matrix product representation of Prolhac, Evans and Mallick. Consequences of the construction include: a simple method for sampling exactly from the stationary distribution for the system on a ring; results on common denominators of the stationary probabilities, expressed as rational functions of $q$ with non-negative integer coefficients; and probabilistic descriptions of "convoy formation" phenomena in large systems.Comment: 54 pages, 4 figure

Dual-fuel, dual-mode rocket engine

The invention relates to a dual fuel, dual mode rocket engine designed to improve the performance of earth-to-orbit vehicles. For any vehicle that operates from the earth's surface to earth orbit, it is advantageous to use two different fuels during its ascent. A high density impulse fuel, such as kerosene, is most efficient during the first half of the trajectory. A high specific impulse fuel, such as hydrogen, is most efficient during the second half of the trajectory. The invention allows both fuels to be used with a single rocket engine. It does so by adding a minimum number of state-of-the-art components to baseline single made rocket engines, and is therefore relatively easy to develop for near term applications. The novelty of this invention resides in the mixing of fuels before exhaust nozzle cooling. This allows all of the engine fuel to cool the exhaust nozzle, and allows the ratio of fuels used throughout the flight depend solely on performance requirements, not cooling requirements

Reconstruction thresholds on regular trees

We consider a branching random walk with binary state space and index set $T^k$, the infinite rooted tree in which each node has k children (also known as the model of "broadcasting on a tree"). The root of the tree takes a random value 0 or 1, and then each node passes a value independently to each of its children according to a 2x2 transition matrix P. We say that "reconstruction is possible" if the values at the d'th level of the tree contain non-vanishing information about the value at the root as $d\to\infty$. Adapting a method of Brightwell and Winkler, we obtain new conditions under which reconstruction is impossible, both in the general case and in the special case $p_{11}=0$. The latter case is closely related to the "hard-core model" from statistical physics; a corollary of our results is that, for the hard-core model on the (k+1)-regular tree with activity $\lambda=1$, the unique simple invariant Gibbs measure is extremal in the set of Gibbs measures, for any k.Comment: 12 page

LAND-GRANT ORGANIZATION TO MEET THE FUTURE

Teaching/Communication/Extension/Profession,

No I don’t like where you come from, it’s just a satellite of London: High Wycombe, the Sex Pistols and the punk transformation

The journey from proto-punk to punk occurred at high speed in many of London’s satellite towns. Among these, the town of High Wycombe in the home counties offers a narrative that can trace an involvement in the earliest stages of that journey as a result of performances by leading British punk group the Sex Pistols. This article explores three Sex Pistols-related events that are used to map three clear phases of the proto-punk to punk transformation. The first wave notes the blurred lines in the fluid symbiotic relationships between proto-punk in London and its satellite towns. Drawing on Crossley, I note that London’s networked punk ‘music world’ was reliant on both cultural commuters and activities in the provinces. I propose a further, fluid notion of transivity that shows the relationship between local and ‘commuter’ punks is needed. The second wave shows the damaging aspect to High Wycombe’s punk identity as, due to its close proximity to London, many if its key actors would move to the capital as soon as they were able to. They escaped from the ‘boredom’ of High Wycombe – the commuter town – to go to the ‘excitement’ of cosmopolitan London to live their dreams. The third wave reveals a moment of class and regional cohesion, through which a High Wycombe Punk identity emerges during the summer of 1977. This occurs among the first and second wave participants who remained and the newer school-aged punks. Finally, the article introduces the local punk terrain beyond the timeline under investigation. Here, regional and class difference became played out through violent interactions between Wycombe punks and skins, and punk scenes from other towns. Here we see the assertion of ‘Wycombe Punk’ as a type

Terrorism and the resilience of cities

The September 11 attacks in New York and Washington have forced Americans to confront the fact that to live or work in a large city is to be at greater risk of large-scale terrorism. What do these risks, and the public perception of them, imply for cities in general and the future of New York City in particular? In this article, the authors begin their exploration of this issue by examining why cities exist in the first place. To conduct their analysis, they simulate two key theoretical models of economic geography, using data that approximate the characteristics of a major U.S. city as well as estimates of the costs of the September 11 attacks. The authors conclude that the very forces that lead to city formation also lead cities to be highly resilient in the face of catastrophes such as terrorist attacks. They argue that New York City in particular is likely to continue to thrive despite any ongoing terrorist threat.War - Economic aspects ; Urban economics ; Cities and towns ; Economic conditions - New York (N.Y.) ; Federal Reserve District, 2nd

An economic analysis of liquidity-saving mechanisms

A recent innovation in large-value payments systems has been the design and implementation of liquidity-saving mechanisms (LSMs), tools used in conjunction with real-time gross settlement (RTGS) systems. LSMs give system participants, such as banks, an option not offered by RTGS alone: they can queue their outgoing payments. Queued payments are released if some prespecified event occurs. LSMs can reduce the amount of central bank balances necessary to operate a payments system as well as quicken settlement. This article analyzes the performance of RTGS systems with and without the addition of an LSM. The authors find that, in terms of settling payments early, these mechanisms typically outperform pure RTGS systems. However, there are times when RTGS systems can be preferable to LSMs, such as when many banks that send payments early in RTGS choose to queue their payments when an LSM is available. The authors also show that the design of a liquidity-saving mechanism has important implications for the welfare of system participants, even in the absence of payment netting. In particular, the parameters specified determine whether the addition of an LSM increases or decreases welfare.Payment systems ; Banks and banking, Central ; Bank liquidity

The XP customer team: A grounded theory

The initial definition of XP resulted in many people interpreting the on-site customer to be a single person. We have conducted extensive qualitative research studying XP teams, and one of our research questions was “who is the customer”? We found that, rather than a single person, a customer team always exists. In this paper we outline the different roles that were typically on the team, which range from the recognized “Acceptance Tester” role to the less recognized roles of “Political Advisor” and “Super-Secretary”